If the software thought you were running it under a debugger it would try to trash the disk. Unfortunately several errors made the software think it was running under a debugger even if it wasn't, and a few people lost data.
I'd imagine doing something like this nowadays would result in litigation. There are stories of older apps doing all kinds of unsavory shenanigans:
(http://www.geocities.ws/johnboy_tutorials/bt.html) (yes, that IS a geocities link)
Some as benign as popping a "gotcha" message like the author here, some as evil as nuking the registry or boot sector. The armchair lawyer in me wonders what would happen if someone who had their drive trashed by gotcha code like this initiated legal action.
(http://books.google.co.uk/books?id=eo4Otm_TcW8C&pg=PT509...)
If the software thought you were running it under a debugger it would try to trash the disk. Unfortunately several errors made the software think it was running under a debugger even if it wasn't, and a few people lost data.